Hanging out by the river, no one would suspect Mamimi is a girl with a dark past. She's been obsessed with a videogame. There's been a string of fires around town. If that's not enough, there's something growing inside Naota's head.

Though he's carried around his brother's bat, Naota has never hit anything. Now his brother's gone, it's Naota's turn to prove his worth. The baseball team doesn't seem to be doing so well. What is Haruko doing playing for the other team?